a= dv/dt => The acceleration determines the slope of the velocity graph. So a constant acceleration line means an increasing velocity, Acceleration = 0 means a constant velocity. You must study the graphs you are given and piece together the various graphs.

Remember that v = dx/dt so you can do the same thing with the velocity line to create a displacement graph.

Probably what you want for this is the fact that the integral is the area under the curve.

Given a graph for a(t), estimate the area under the curve from 0 to t for a number of different values of t. That will give the graph for v(t). It is probably enough to remember things like: if the graph of a(t) is above a=0, then v(t) is increasing, if below, then v(t) is decreasing. if the graph of a(t) is horizontal, then v(t) increases (or decreases) linearly with slope given by the a value.

Once you have a rough graph for v(t), x(t) is the area under that curve. Repeat the process to get a graph of x(t).